In this chapter, the principles of 3D shape measurement are presented, focusing on techniques that utilize various types of wave-based scanning. These methods operate by analyzing how waves, such as electromagnetic, ultrasonic, light or X-rays, are reflected or transmitted through objects. Today, such techniques are widely employed to reconstruct the three-dimensional geometry of objects and environments. Additionally, tomographic imaging using mainly but not only X-rays enables the non-contact acquisition of 3D volumetric data from within an object. All of these methods rely on the fundamental physical interactions between waves and matter, as introduced in Chap. 1 . This chapter provides a deeper description of the key components involved in measurement systems and the data processing algorithms used. The aim is to enhance the reader’s understanding of the core principles, capabilities, and limitations of these 3D scanning techniques.